1. Field of the Invention
The present invention relates to a paper sheet separating and take-out device which separates and takes out paper sheets in an accumulated state one by one.
2. Description of the Related Art
Conventionally, as a take-out device that takes out a plurality of paper sheets in an accumulated state one by one, there is known a device that causes a take-out roller to contact with a paper sheet in one end of an accumulating direction to rotate the roller and takes out the paper sheet in a direction substantially perpendicular to the accumulating direction (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2003-341860). The device is incorporated into, for example, postal matter processing devices that inspect and sort a plurality of postal matters.
The take-out device includes a separating mechanism that separates second and subsequent paper sheets that are carried along with a paper sheet taken out by the take-out roller. The separating mechanism has a feed roller and a separating roller. The feed roller takes out a paper sheet to be taken out on the same side as the take-out roller and is arranged on a downstream side of the take-out roller. The separating roller is arranged across the taken-out paper sheet from the feed roller. A plurality of separating mechanisms are occasionally arranged along a take-out direction of the paper sheets.
The feed roller rotates so as to feed the taken-out paper sheet in a forward direction. On the other hand, the separating roller rotates in conjunction with the feed roller when one paper sheet intervenes or no paper sheet is present between the feed roller and the separating roller. When a plurality of overlapped paper sheets pass between the separating roller and the feed roller, the separating roller applies a separating torque which directs towards a direction opposite to the take-out direction to second and subsequent paper sheets on the side of the separating roller. As a result, the second and subsequent paper sheets are braked so as to be separated from the first paper sheet.
In this kind of the separating mechanism, the feed roller frequently contacts with the separating roller and rotates. The separating mechanism uses rubber rollers having large friction coefficient in order to heighten a separating performance. Therefore, when the rollers contact with each other, they wear over time so that the separating performance is degraded. Particularly, when the take-out speed of the paper sheets is heightened, the abrasion of the rubber rollers progresses, so that its life is noticeably shortened. For this reason, it is difficult for the above conventional device to maintain its initial performance and improve its throughput.
On the other hand, as a device that takes out paper sheets onto a conveyance path, devices that include a negative pressure generating device are known (see, for example, EP0589789B1, EP0645330B1 and Jpn. Pat. Appln. KOKAI Publication No. 10-231040). The negative pressure generating device allows paper sheets to be adsorbed to a belt which contacts with the paper sheets to move in a take-out direction. Further, the negative pressure generating device allows paper sheets to be adsorbed to a belt which moves while applying a negative pressure to the paper sheets through a plurality of holes on the belt.
Particularly, the device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-231040 has a plurality of separating rollers arranged into a nested pattern with respect to a delivery belt. The separating rollers have rubber on their outer peripheries and apply a resistance force in a direction opposite to a delivery direction to multiply-fed paper sheets such that the second and subsequent paper sheets that are carried along with the paper sheet adsorbed to and delivered by the delivery belt are separated. The separating rollers have a supporting structure such that the rollers can be oscillated by collision of paper sheets.
When the separating rollers which apply the resistance force to the multiply-fed paper sheets oscillate and leave the conveyance path of the paper sheets, the resistance force cannot be applied to the paper sheets while the separating rollers pop up due to the collision of the paper sheets. As a result, the multiply-fed paper sheet separating ability is degraded.
The separating rollers used in this device are rubber rollers. Therefore, similarly to the separating roller in Jpn. Pat. Appln. KOKAI Publication No. 2003-341860, they wear over time. For this reason, it is difficult for also the device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-231040 to maintain its initial performance for a long time and improve its throughput.
As this kind of the device for taking out paper sheets, a device is known that has a separating roller which always rotates in a direction opposite to the take-out direction of paper sheets in a state that it generates a negative pressure on its peripheral surface so as to adsorb the paper sheets is known (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 8-188279). The separating roller has a plurality of holes on its peripheral surface for generating a negative pressure, and returns second and subsequent paper sheets that are carried along with a paper sheet taken out by a feed roller in an opposite direction.
The separating roller, however, is arranged fixedly so as to be opposed to the feed roller for feeding taken-out paper sheets in a forward direction via a constant space. For this reason, when a comparatively thick paper sheet is sent between these rollers, jam easily occurs. Particularly, in the case where a comparatively thin paper sheet is brought together with a comparatively thick paper sheet, the thin paper sheet is potentially bent or damaged when the thin paper sheet is returned in the opposite direction by the separating roller.